EF在SqlQuery中生成“不支持指定的方法”错误

Question

I am currently using Entity Framework 5 I've tried to code the following:

var result = context.Database.SqlQuery<Entity>("SELECT * FROM ref.Entity");

But I get the following error:

Specified method is not supported.

Can anyone show me a resolution to this issue?

stack trace

"at EFProviderWrapperToolkit.DbConnectionWrapper.CreateDbCommand()\\r\\n at System.Data.Common.DbConnection.CreateCommand()\\r\\n at System.Data.Objects.ObjectContext.CreateStoreCommand(String commandText, Object[] parameters)\\r\\n at System.Data.Objects.ObjectContext.ExecuteStoreQueryInternal[TElement](String commandText, String entitySetName, MergeOption mergeOption, Object[] parameters)\\r\\n at System.Data.Objects.ObjectContext.ExecuteStoreQuery[TElement](String commandText, Object[] parameters)\\r\\n at System.Data.Entity.Internal.InternalContext.ExecuteSqlQuery[TElement](String sql, Object[] parameters)\\r\\n at System.Data.Entity.Internal.InternalContext.ExecuteSqlQueryAsIEnumerable[TElement](String sql, Object[] parameters)\\r\\n at System.Data.Entity.Internal.InternalContext.ExecuteSqlQuery(Type elementType, String sql, Object[] parameters)\\r\\n at System.Data.Entity.Internal.InternalSqlNonSetQuery.GetEnumerator()\\r\\n at System.Data.Entity.Internal.InternalSqlQuery 1.GetEnumerator()\\r\\n at System.Linq.SystemCore_EnumerableDebugView 1.GetEnumerator()\\r\\n at System.Linq.SystemCore_EnumerableDebugView 1.get_Items()"

Answer 1

This is mentioned in "Known Problems" section on codeplex "Community Entity Framework Provider Wrappers" site . Citing:

Directly executing store commands using methods such as ObjectContext.ExecuteStoreCommand or ObjectContext.ExecuteStoreQuery is not supported. You may, however, create a DbCommand from the database connection using code such as this:

  using EFProviderWrapperToolkit; ... context.Connection.GetStoreConnection().CreateCommand() 

Answer 2

The answer is quite simple. I am not sure if you have the source code of EFProviderWrapperToolkit, you should get it and have a look at it. You will notice that DbConnectionWrapper, which inherits from DbConnection it overrides CreateDbCommand method but does not provide any functionality for it, instead it throws and exception.

/// <summary>
        /// Creates and returns a <see cref="T:System.Data.Common.DbCommand"/> object associated with the current connection.
        /// </summary>
        /// <returns>
        /// A <see cref="T:System.Data.Common.DbCommand"/> object.
        /// </returns>
        protected override DbCommand CreateDbCommand()
        {
            throw new NotSupportedException();
        }